A modem or other telephone apparatus to which a call is addressed is sometimes required to display the identity of, or other relevant information pertaining to, a caller without accepting the call. Such a feature is commonly known as "caller ID".
In prior art caller ID arrangements, known for example from U.S. Pat. Nos. 4,672,660 and 4,598,179, the receiving apparatus goes off-hook, then identifies the caller information and finally determines whether the call may proceed.
It would be desirable for the receiving apparatus to be able to identify the caller information and determine whether the call may proceed before the apparatus goes off-hook and the telephone exchange-recognises the call as accepted.